Whistles are used by judges in sport tournaments for example, in signaling a start, breaks, resumption, and the end of a game, and warnings the players to follow the rules of the game. Whistles are based on a fundamental principle that an edge tone is produced by an edge inside a whistle when air is blown into the mouth (air inlet) of the whistle and that the edge tone is then amplified by resonance in a resonance chamber of the whistle.
An example of such whistles is disclosed in Japanese Patent Laid Open Publication No.8-211881. This publication teaches a whistle having a mouthpiece into which air is blown, a duct for passing the air to an edge and a resonance chamber where the blown air oscillates in resonance with an edge tone, and a sound outlet in the form of opening formed between the duct and the resonance chamber for radiating the resultant whistle sound outwardly. The whistle disclosed in this publication has a multiplicity of holes in the wall of the resonance chamber, which holes can be blocked or opened by turning a blocking member to change the tone of the whistle.
In this whistle, although the tone is alterable, its volume cannot be changed, unless a great amount of air is quickly breathed in. However, lung capacity, i.e. an amount of air that a person can breathe at a time, greatly varies from person to person, so that a person having a smaller lung capacity can produce only a small whistle sound, especially when he is not familiar with whistling, and then the sound is difficult to hear in a noisy place. If such a person could give a large blast on a whistle, he would not be able to continue blasting for a long time. It is therefore difficult for him to blow a whistle loudly.
In view of such drawbacks of conventional whistles, the invention is directed to a whistle capable of producing a louder sound containing many higher harmonics under normal breathing.